In these knitting machines, for example, circular knitting machines which have a cylindrical sinker carrier which can be driven to rotate with vertical run of its central axis around it and which is located within the stator of the machine which has the form of a cylindrical jacket according to external shape and which coaxially surrounds the sinker carrier, the sinker carrier contains a plurality of sinkers, for example 2000 which are located next to one another in edge-open radial grooves which are equidistant in the azimuth direction, with a vertical run which is parallel to the center longitudinal axis of the plate carrier, in each of these grooves being a sinker which can move up and down.
For controlled driving of the sinkers in this regard, which takes place by relative rotational movements of the sinker carrier to the machine stator which is made as a cam carrier, the sinkers are provided with clearing feet which have contour edges which run transversely to the sinker guide direction; by their sliding away the deflections of the control sinkers are controlled via a drive cam of the stator provided with a clearing edge. In this case the control sinkers, by the action of a minimum prestress per control spring which proceeds from a base body of the sinker and which has a stretched rod shape in terms of basic shape, and which has a free end which is supported to slide on the base of the guide groove of the control sinker, are displaced into the engagement position of their clearing foot which transfers deflection driving, with the clearing edge of the clearing cam of the cam carrier. They can furthermore be displaced by control elements of the cam carrier and sinker carrier which work by force fit-form fit into a base position, in which the drive engagement of the clearing feet is cancelled with the clearing edge of the clearing cam. In this base position the sinkers can be fixed by the retaining force of a permanent magnet arrangement which has a holding action which can be cancelled by compensatory triggering of an electronically controllable magnet arrangement, so that the sinkers can be released by the action of the control springs for assuming the clearing position.
In known sinkers of this type (DE-39 15 684 C1) the control springs are made as spring steel rods with a cross section which is round, rectangular or uniform over its entire resilient length and with flattened anchoring pieces which are rectangular, flat-plate formed according to basic shape, and which has a thickness which is less than that of the sinker material which is equal to the diameter of the spring leg measured at a right angle to the longitudinal surfaces of the sinker, in flat groove-shaped depressions with cheek contour which is matched exactly to the contour of the anchoring pieces, anchored by force fit-form fit, the resilient rod passing through a short opening of the sinker material which discharges into an anchoring depression. To secure the spring rod against disarrangements in the anchoring depression of the sinker, on the edges of the depression which the anchoring section of the spring rod adjoins, there is caulking of the sinker material which in interaction with notches of the anchoring section yields a force-fit/form-fit connection of the spring rod with the sinker overall. The spring rods are fixed on the sinkers such that the center longitudinal axes of the spring rods run in the longitudinal center planes of the sinkers which extend between their large area shaft boundary surfaces.
The known sinkers are subject to at least the following disadvantages:
Production of the sinkers is complex and expensive, since the anchoring depressions of the sinkers and the anchoring end pieces of the spring elements must be matched to one another within narrow tolerances; this requires high-precision machining of the surfaces which touch one another. Joining of the sinker elements to be connected to one another requires time-consuming mounting effort which for its part is costly. Finally the caulking of the edges of the anchoring grooves of the sinker base body with the edges of the anchoring pieces of the springs in many cases can lead to undesirable bulges of the sinker shaft, by which likewise time-consuming remachining can become necessary. In addition, even minor imprecision in the anchoring area can lead, at least after some time, to loosening of the spring-sinker anchoring and to fracture thereof, for which reason sinker sets of the known type must be completely replaced after a certain operating time of the machine. This contributes significantly to operating costs of knitting machines equipped with sinkers of the known type.
The object of the invention is therefore to improve a sinker of the initially mentioned type such that with production costs which are clearly reduced nevertheless it can be built with improved quality and thus increased service life.
This object is achieved as claimed in the invention by the sinker including its control springs being made as a single-piece spring steel part, by the width (h) of the control spring, measured at right angles to their neutral bending line on the base side of the spring on which it adjoins the sinker base body, having a larger value than on the free spring end with which the control spring can be supported on the base of the guide groove, and by the control spring on its base side with smooth curvature which widens the base area adjoining the sinker base body.
The control sinker as claimed in the invention yields at least the following production and functional advantages:
It can be produced very efficiently as a stamping which requires if necessary only very little subsequent grinding and therefore can also be produced very economically.
The configuration of the sinker and control spring which is possible by the integral design thereof with a configuration of the spring base area which widens with a smooth curvature and which also passes into the sinker base body with a smooth curvature has the advantage that notch effects in the base area of the control spring and load-induced wear in the area in which the spring adjoins the sinker base body can be almost completely prevented and thus favorably high service lives of the sinker as claimed in the invention can be achieved.
This also applies with reference to the dimensioning of the spring width which decreases from the base side of the springs to its free end, by which on the one hand a uniform distribution of the bending load over the length of the control spring and on the other hand the desired force/spring path characteristic of the springs can be stipulated, which yields a favorable, especially rapid (switch) response behavior of the springs with a width in the preferred configuration of the control spring on the support end which corresponds to between 80 and 120% of the thickness of the sinker material and on the base side of the spring to between 150 and 250% of this thickness.
One especially advantageous configuration of the control sinker which is likewise used to achieve uniformity of the distribution of the prestress of the springs over their length consists in that the control springs in the clearing position of the sinker runs parallel or roughly parallel to the extended control shaft of the sinker which is provided on a middle section of its length on its longitudinal side facing away from the spring end with the clearing foot, and in that the control spring in its released configuration which it assumes before installation in the sinker carrier has a curvature which points away from the shaft with a radius of curvature which is greater than the spring length and corresponds to 5 to 8 times the spring length, preferably roughly 6.5 times.
If the radius of curvature with which the control spring smoothly adjoins the base body and the control shaft of the sinker has a value between 1.5 times and twice the value of the base width of the control spring, for a relatively large base width thereof a notching action in the spring base area can be reliably precluded.
In the preferred configuration of the control sinker its spring base, starting from which the smooth curvature begins with which the control spring passes into the sinker base body and the sinker control shaft which projects over the support end of the spring in the longitudinal direction, likewise with a smooth curvature, adjoins a support projection which points toward the free spring end, which is located on the spring side opposite the control shaft, which proceeds from the sinker base body, and which on its side facing away from the control spring can be supported with one obtuse-angled edge which marks one tilt axis of the sinker on the base of the guide groove.
This yields an arrangement of the control spring base which is so-to-speak displaced into the sinker base body, and with a stipulated support point of its spring end on the base of the guide groove there is a prolongation of the spring which in turn yields the possibility of a favorable stress distribution over the spring length.
For this purpose, to achieve a clearly increased service life of the spring, it is enough if length l.sub.b of the control spring section near the base and extending between the support projection and the control shaft of the sinker is between 7 and 15% of the spring length L'.sub.F, preferably around 10% thereof.
In this configuration of the control sinker it is a good idea if the base of its control spring with the same radius of curvature smoothly adjoins the contour edges of the control shaft and the support projection which run adjacent to it, parallel or almost parallel to its longitudinal edges, to prevent undesirable notch effects it being sufficient if the radii of curvature with which the base of the control spring smoothly adjoins the adjacent control shaft and the support projection have values between the value of the base width of the spring and 1.5 times the value, preferably roughly 1.1 times the value.
Other details of the invention result from the following description of the embodiments using the drawings.